The invention relates to a power press for the manufacture of profiled bodies. More particularly, it relates to a power press for the manufacture of stamped profiled bodies from a non-ascending mixture of a thermohardening bonding agent mixed with fibrous materials, which has at least an inner pressing tool part and an outer pressing tool part which engages the inner tool part and whose surfaces are profiled according to the profiled body to be pressed.
Power presses for the manufacture of profiled bodies of the above mentioned general type are known in the art.
One such power press is disclosed, for example, in the DE-PS No. 25 48 739. This power press is used to press profiled bodies such as outer and inner lining profiles for highrise constructions for lining balconies, table plates and the like, pressed from a non-ascending mixture with a thermohardening bonding agent mixed with fibrous materials.
The non-ascending mixture is composed mostly from ligno cellulose-containing fibrous materials, such as crushed and dried shavings, fibers of crushed sugar cane, etc, mixed with a thermohardening artifical or synthetic resin, such as melaminurea formaldehyde-or phenol formaldehyde resin. Instead of crushed and dried wood or fibers of crushed sugar cane, threads of another material, such as glassfibers, matte wood or asbestos fibers, either singularly or mixed together, can be used and to which corresponding preferably organic binding agents are added.
Usually the profiled bodies are manufactured in such a way that a rough pressed block is first made from the mixture by fold pressing, which can then be provided with a cover layer on its lower side, that is, on the outer surface of the profiled body which is not used as a visible side. For this purpose a rough pressed block which is already very similar to the completed profiled body is pressed from the mixture in a power press. Although during the preliminary pressing of the profiled body the amount of heat necessary for thermohardening of the binding has not been applied, the rough pressed block is already a firm body capable of being handled.
From the rough pressed block, by heat pressing in another power press the completed profiled body is produced.
During the hot pressing, the profiled body as a rule is simultaneously provided with a cover layer, which consists usually of at least one layer, namely, a decorative layer, for instance of a texture, a veneer, or print on paper foil or a plastic foil, over which a transparent protective layer can be arranged. As a protective layer, a so-called overlay-paper is used consisting of a non-filled alpha-cellulose paper on glass fiber fleece which is soaked with a Duroplast mostly on the melamin basis. The transparent protective layer can also be made in such a way that the decorative layer has a stronger resin layer. The known power press for manufacturing the aforementioned profiled bodies have proved to a large extent to be a success. Nevertheless, certain difficulties occur when the profiled body produced in this manner has a strongly structured upper surface or configuration.
In two stage power presses it is imperative that the pressing tool during the second hot pressing step act at the identically same place on the profiled body to be pressed as it did during the first hot pressing step. When this does not happen, then the profiled body to be pressed would appear damaged. If the pressing tool in the second hot pressing step acts at another place on the profile body to be pressed, it is responsible for the shrinkage of the profiled body occurring during the first heating process.